1. Field of the Invention
This invention relates generally to packaging and, more particularly, to an absorbent package which, when placed in a sealed package or container, substantially eliminates the deleterious effect that certain gases, which are typically present in the head space of the sealed package or container, have upon the particular item stored within the package or container.
2. Description of the Background Art
In the art of packaging, the skilled artisan is continuously endeavoring to develop techniques for maintaining the quality and integrity of items stored in packages, such as, by prolonging the shelf life of the particular item or items contained in the package. Items stored within a package are typically affected by the surrounding environment and are oftentimes adversely affected by the gases present in the head space or free space within the interior of the package.
One specific gas that is problematic in this context is oxygen. Specifically, where the packaged items are foodstuffs, the presence of oxygen can create an environment in which molds or eumycetes, bacteria and insects will thrive, which ultimately leads to putrefaction and a change in the quality of the packaged foodstuffs, which are typically exemplified by oxidative color and flavor changes. Additionally, oxidation of the foodstuffs can adversely affect their taste. Cheeses, nuts, coffee, processed meats, cakes, confections and dried fruits are representative of some of the foodstuffs which can be adversely affected in the presence of oxygen.
The need to minimize the concentration of oxygen within a package containing foodstuffs has not gone unrecognized. U.S. Pat. No. 4,332,845 describes an oxygen absorbent-containing bag fabricated from water impermeable laminated sheets. The oxygen absorbent contained within the bag absorbs oxygen present in its surrounding environment, such as when it is placed within a package containing foodstuffs, thereby preventing putrefaction or a change in the quality of the foodstuff. Similarly, U.S. Pat. No. 4,485,133 describes an oxygen absorbent package which includes a water impermeable multi-layer structure, intended to accommodate an oxygen absorbent to prevent damage to the foodstuffs contained in a package.
The adverse affect of oxygen is further manifested where the packaged items are metallic and subject to oxidation which ultimately leads to product degradation or, at best, an aesthetically unacceptable product. This problem is typically encountered in the art of manufacturing electronic components.
It is also desirable to minimize the amount of carbon dioxide present in the head space of sealed packages, especially in the coffee packaging art. When coffee is packaged, whether in the form of roasted or ground coffee or whole coffee beans, the package will balloon as evolved carbon dioxide is liberated from the coffee and eventually the container will break and its contents will be ruined. Even in the event that the package does not rupture, the evolved gases will create an expansion of the package that will render the package unattractive from a consumer standpoint.
In response to this problem, those skilled in the art have developed certain degassing procedures, which suffer a host of disadvantages from the perspective of cost, equipment and time. Another approach to solving this problem is by packaging coffee with an absorbent package containing carbon dioxide sorbents, such as those described in U.S. Pat. No. 4,552,767. However, in these systems, additional problems have been encountered. The problem concerns the slow uptake of CO.sub.2, which results in unequal pressure on the inside and outside of the walls of the coffee container. The container, a bag comprised of a lamination of paper, foil and sealants, softens, distorts and collapses over time, rendering the product unsuitable for shipment and distribution.
The absorbent package of the present invention is offered as an improvement over those which have been heretofore provided. In addition to absorbing unwanted gases from the head space within sealed packages, the absorbent package of the present invention has a wide range of potential applications, inasmuch as it is offered as a means for controlling the conditions of its surrounding environment and is particularly well adapted to control or reduce odors and moisture, which is advantageous in the packaging of pharmaceutical products.
The absorbent package of the present invention possesses some of those characteristics typically exhibited by nonwoven, long fibered materials. Generally speaking, a nonwoven, long fibered material and the absorbent package of this invention are both gas and water permeable, flexible, heat sealable and have a mono-layered structure.
The fibrous web structure used to make the absorbent package of the present invention is somewhat similar, in certain limited respects, to TYVEK.RTM., a spunbonded olefin available from DuPont Company, Wilmington, Delaware. Notwithstanding, the package of this invention exhibits certain characteristic properties which make it a superior absorbent package when compared to packages fabricated from TYVEK.RTM.. Thus, while TYVEK.RTM. is a known material used in controlled atmosphere packaging applications, it possesses certain shortcomings relative to the absorbent package of this invention. Specifically, it does not heat seal to itself easily. Rather, hot melts and pressure sensitive adhesives are required to obtain strong seals. Additionally, TYVEK.RTM. begins to melt at about 275.degree. F. and destroys the fiber structure, reducing both flexibility and tear strength in the seal area. Furthermore, TYVEK.RTM. is impervious to water.